JPH0657915B2 - Antistatic carpet tiles and process for making such carpet tiles - Google Patents

Description

TECHNICAL FIELD The present invention relates to an antistatic carpet tile and a method for manufacturing this type of carpet tile.

[Prior Art] A floor covering material such as a carpet tile, for example, accumulates a large amount of static electricity when a person walks on the floor covering material or moves an article such as furniture in contact with the floor covering material. When the accumulated static electricity is rapidly discharged to the floor covering material, it gives an unpleasant feeling to humans and hinders the functions of computers and electronic devices. Static electricity storage and discharge provides a conductive path from the surface of the carpet to the electrical ground and the resistance to the floor surface agent (ie bulk resistance and surface resistance) is within certain criteria, such as computers more sensitive to computer and electronic component manufacturers. , Can be ensured and minimized to within the standards required to protect devices with electronic components and microchips. Typically, this type of criterion requires a minimum of 5 × 10 ⁵ Ω and a maximum of 2 × 10 ¹⁰ Ω in surface and bulk resistance. Moreover, for safety, there is often a desired minimum resistance value of 10 ³ -10 ⁴ Ω.

Carpet materials, especially carpet tiles, have been developed which prevent the generation or accumulation of static electricity and which can dissipate the static electricity rapidly without danger to humans or equipment.
However, to date, floor coverings of this kind have not been entirely satisfactory. An antistatic floor coat can be manufactured by applying an antistatic top coat material to the surface of the floor. However, typically this type of antistatic treatment is not permanent and results in soiling of the floor covering, and is generally not very effective under low and relative humidity conditions. Permanent or electrostatic conductivity in fibrous floor coverings can be created by incorporating conductive fibers or yarn members into the floor covering (eg, carpet tile). Conductive fiber members of this type are, for example, composed of fine fine metal wires or metal-coated wires as yarn members, or, for example, of carbon-filled carbon-containing core yarns or fibers mixed with non-conductive surface fibers or yarns. be able to. This type of permanent protection often provides both low static electricity and electrical conductivity at the carpet surface caused by interactions between the carpet surface and people and articles. However, the conductive fiber surface does not, by itself, provide effective conductivity through the surface of the carpet. That is, it does not give acceptable conductivity or bulk resistance (so-called capacitive resistance).

Carpet tiles are manufactured which are incorporated into the carpet's fiber surface to secure the carpet's fiber surface and to secure these members through the use of a conductive precoat or backing layer to dissipate generated static electricity very quickly. ing. Typically, conductive precoats of this type include conductive particles (such as conductive particles such as metal particles, especially finely divided carbon black particles) to enhance the conductivity, such as styrene-ptadiene latex. It is made of polymer material. Carpet tiles of this type, or other carpet materials, must also have a relatively thick backing layer to ensure dimensional stability of the carpet tile in use and a leveling surface for the carpet tile. Although a wide variety of polymeric materials can be used, the most prevalent materials currently used for lining commercial carpet tiles are atactic polypropylene, bitumen and polyvinyl chloride. This kind of material must be non-conductive,
Therefore, the charge cannot be easily grounded or conducted to the back side of the carpet tile.

In general, it has been found that the use of antistatic or conductive chemicals in relatively thick backing layers, for example particulate materials such as carbon black particles, with polymeric backings is not sufficient. This is because the amount of carbon black needed to obtain the desired conductivity or antistatic effect results in a significant increase in viscosity or often affects the lining chemical properties. Furthermore, incorporation of this into the backing material with other antistatic additives such as, for example, metallic fatty acid soaps, glycols, often changes the chemical and mechanical properties of the backing material resulting in unsatisfactory quality and properties. . For example, the use of stearic acid compounds in solid bitumen linings, when used in the manufacture of carpet tiles, often affects the adhesion of bitumen and further weakens the mechanical properties of bitumen or bitumen fillers (eg lime, backing). . A carpet tile and a method for manufacturing the same are described in British Patent Publication No. 2057353B published on March 28, 1984, which is incorporated herein by reference.

[Problems to be Solved by the Invention] Therefore, a surface of a conductive fiber surface having improved conductivity and more effective and improved antistatic property which avoids the drawbacks associated with the conventional surface materials described above. It is desirable to provide a covering and a method of making the same.

[Means for Solving the Problems] The present invention relates to a surface covering material for a fiber surface having an antistatic property or improved conductivity, and a method for producing and using the same. In particular, the present invention relates to antistatic carpet tiles for use in, for example, the computer, electronics and office environments to prevent damage to sensitive computers and electronic devices and methods of making and using the same.

The antistatic conductive carpet or surface covering of the present invention comprises a fiber sided surface and a backside layer, with a plurality of conductive material columns extending from the backside of the carpet through the backing layer to the bottomside of the carpet. Then, an electric path is formed from the back surface of the carpet to the back surface of the carpet by penetrating the island-shaped conductive material column.

In particular, the present invention provides that carpet tiles have primary backing sheets (typically non-woven polypropylene, polyester, hemp,
Antistatic carpet tile having a fiber surface fixed to a sheet material such as glass fiber used as a primary backing sheet) and a frecoat layer that acts to fix this fiber surface to the back surface of the primary backing sheet I will provide a. The carpet comprises a relatively thick solid or foam backing layer, or a combination thereof, which may be formed as one or several layers, which further comprises a dimensionally stable sheet material such as a glass fiber sheet. You can If desired, a secondary backing layer of sheet material such as polyester can be secured to the backside of the backing layer.

Carpet tiles have a plurality of spaced columns of conductive material formed in the backing layer and extending from the back side of the carpet tile to approximately the precoat layer and the back side of the primary backing sheet, from the front side of the carpet to the back side of the carpet. An electrical path is formed to enhance conductivity and provide improved conductivity or bulk resistance of 1 × 10 ¹⁰ Ω / square (□) or less, typically 1 × 10 ⁶ Ω / □ or less.

If desired, the antistatic carpet tile may optionally further comprise on the back surface one or more layers of conductive material, such as a thin coating layer or strip, to provide a conductive column on the back surface of the carpet tile. It is also possible to form an electrically conductive strip that connects the ends of the carpet tile and extends over substantially the entire back surface of the carpet tile to connect the spaced column ends on the back surface of the carpet tile. Further, the conductive layer or strip may be composed of a conductive adhesive layer that secures the carpet to the floor.

In a particularly preferred embodiment, the antistatic carpet of the present invention has a fibrous surface comprising conductive fibers or yarns and the precoat is a conductive precoat, i.e. antistatic properties such as carbon particles or metal particles. Carpet tiles containing additives and further having one end of the conductive column projecting into the precoat and the other end extending to the conductive strip or back of the carpet substantially perpendicular to the back of the carpet. There is. In fact, the conductive or antistatic additives can be topcoated on the surface of the carpet, incorporated into the backing layer, or incorporated into either the sheet material used in the carpet, Typically, the backing layer is non-conductive or poorly conductive and islands of multiple conductive materials, such as islands approximately evenly spaced in one dimension of the carpet tile, are effective for grounding. Form an electrical path.

Suitable for use in computer and electronics industry and about 1
An effective antistatic conductive carpet having a bulk resistance value of less than × 10 ⁸ Ω / □ is, for example, polyester,
Formed using carpet tiles having a fiber side of synthetic fibers such as nylon, which has needle punched, fused or tufted type fibers, which have some thin stainless steel yarn or carbon. The synthetic yarn of the core is included to provide electrical conductivity to the carpet surface. Thin stainless steel yarns of this kind can be coated to increase conductivity and can even consist of carbon-filled polymer fibers, for example 6 vs. 12 conductive vs. non-conductive fibers. It is used at a ratio of about 1 conductive yarn.
In addition, carpet tiles of this type also include a primary backing sheet, such as, for example, non-woven polypropylene, and a conductive precoat (eg, a styrene-putadiene latex layer) is used to secure the fibers to the primary backing sheet. The latex precoat may contain carbon particles in an amount that imparts conductivity to the thin precoat layer, such as an amount of 5 to 40 ounces per square yard, and generally provides a conductivity of less than 1 × 10 ⁸ Ω / □. it can.

The carpet tile further has a relatively thick layer of a solid polymeric backing layer, for example bitumen or a layer of bitumen-filler mixture, for example consisting of fine-grained lime and bitumen, for example per square yard.
Use in amounts of 10 to 150 ounces, especially 30 to 120 ounces per square yard. If desired, the backing layer may also contain a texture or scrim of glass fibers or synthetic fibers such as polyester to impart dimensional stability to the carpet tile. It is essential that polymeric backings such as bitumen or lime-filled bitumen are non-conductive. In addition, carpet tiles generally also have a secondary backing layer on their backside, such as a woven polyester layer, to allow the carpet tiles to be easily secured to the ground or rested on the surface for mounting.

Carpet tiles of the present invention typically have a series of solid columns of conductive material consisting of a conductive ink type polymeric material such as, for example, aqueous or volatile organic solvent based inks containing fine carbon particles. Carpets generally have columns of conductive ink extending from the precoat layer, which is generally conductive, or from the back side of the primary layer to the back side, or optionally the back side of the secondary backing sheet. The columns are spaced apart but can vary, and can extend from one end to the other across substantially the entire length of the carpet tile, eg, 1 to 6 inches, more typically 1/2 to 2 inches. They can be evenly spaced apart. A thin coated strip of conductive material, preferably extending over the back surface of the secondary backing sheet, with linearly spaced ends, optionally containing, for example, carbon black particles (eg, SBR latex or conductive ink). It is also possible to connect with a thin strip of conductive material such as. This conductive coating or strip generally extends over the entire surface of the carpet tile and connects the ends of these columns to form islands on the back side of the carpet tile and to the edges of the carpet tile. Instead of the covering strip, a grounded electrical path can be constructed using conductive adhesive to secure the back side of the carpet to the base floor. The carpet tile of the present invention is 1 × when used in a computer room or a room having electronic devices.
In the conductive column and the backside of the column in the conductive precoat layer and the non-conductive thick backing layer, which provides an improved electrical bulk resistance of 10 ⁸ Ω / □ or less, typically 1 × 10 ⁶ Ω / □ or less. Static electricity is rapidly discharged from the conductive fiber surface to the ground through the conductive strip or coating. If desired, the carpet tile can also have columns that are linear, zig-zag or substantially non-uniform or evenly distributed over the entire back surface of the carpet. If highly antistatic carpet tiles are desired, one or more conductive strips connecting the columns or even a grid thereof can be present.

The polymeric materials used for the backing layer are comprised of a wide variety of hot melt or thermoplastic type polymeric materials, including but not limited to: bitumen, vinyl chloride resin, atactic polypropylene, urethane and Ethylene vinyl acetate resin. These polymers are, for example, plasticizers,
Various additives such as flame retardants, curing agents, viscosity index improvers, and fillers such as talc, lime and diatomaceous earth may also be contained. The bitumen used is composed of petroleum-based bitumen or asphalt material and is not derived from or contained in carcinogenic coal tar derivatives,
It shall be suitable for use as a hot melt type carpet lining material.

The present invention further provides a method of making an antistatic or conductive surface covering, such as a carpet tile having a fibrous surface, the method comprising a plurality of spaced apart, such as conductive carbon-containing polymeric ink materials. A thin column of conductive material that extends from the back of the backing layer to the precoat layer or to the back of the primary backing of the carpet material to form a conductive passageway from the surface of the covering material to the back side. At the same time, an improved bulk resistance value is provided. A thin column of conductive material is typically facilitated by injecting one or more spikes or needles containing the conductive material to be deposited into the backing layer to form a thin column in the backing layer. Form. For example, a thin column may have one or more spike-like members mounted on a rotating wheel or reciprocating member coated with a conductive drying liquid, such as a conductive carbon-containing ink, and then applied to the back of the carpet backing layer. It can be formed by intruding a spike-shaped or needle-shaped member of a predetermined length and projecting into the precoat layer or to the back surface of the primary sheet of the carpet tile. The conductive column is formed when the needle-shaped or spike-shaped member is removed, and the conductive material is attached as a column in the penetration hole. Generally, it is used to withdraw needle-like or spike-like members, then re-coat these members with a conductive material and re-enter the back of the backing layer. In general, using a rotating wheel having a plurality of spike-like or needle-like members, the column is formed as a generally discontinuous but predetermined straight path over substantially the entire back surface of the carpet tile.

Further, the method consists of coating the back side of the carpet tile with a conductive coating layer, strip or adhesive to connect the ends of the thin columns on the back side. Generally, the coating may consist solely of strips connecting the column ends on the back side of the carpet tile, but of course a conductive coating covering all or part of the back side of the carpet, either before or after applying the secondary backing layer, if desired. It can also be a layer. In one method of operation, the carpet tile is supported with the fiber side down or up, and then a rotating wheel with a length of needle-like member reaching into the precoat layer is moved laterally of the carpet tile over the support layer. The needle-shaped member is caused to penetrate into the back surface of the backing layer in a predetermined pattern, and after this penetration, the needle-shaped member is extracted and conductive ink is applied to re-cover the surface of the needle-shaped member, and the pattern is repeated. . Since conductive ink generally exhibits a dark color due to carbon black particles, the needle should not penetrate to the surface of the carpet to prevent discoloration of the surface fibers.

EFFECTS OF THE INVENTION The antistatic conductive surface covering material of the present invention, in particular the carpet tile and its manufacturing method, eliminates many of the drawbacks associated with the prior art and is solid with improved electrical resistance. It provides excellent surface coverings, especially carpet tiles, with a non-conductive backing layer.

[Examples] Hereinafter, the production of antistatic carpet tiles according to the present invention will be described with reference to the accompanying drawings, although not limited thereto.
The present invention is equally applicable to the manufacture of many types of antistatic surface coverings and is capable of many modifications, improvements, additions, etc. without departing from the spirit and scope of the present invention. Will be appreciated by those skilled in the art.

The drawing shows a carpet tile having a tufted fiber side woven with a conductive yarn 14 made of a synthetic polymer such as nylon, with the fiber side positioned on a support belt 12. Fiber 14 is the primary lining sheet for polyester 1
6 and fixed in place using a conductive pre-coated SBR latex layer 18 containing conductive carbon black particles. While fixing the bitumen lime lining 20 to the precoat layer 18, a secondary lining sheet 22 made of, for example, polyester fibers is fixed to the back surface of the bitumen lining layer 20.

As described in more detail in FIG. 1, rotating wheel 24
Is positioned above the carpet tile 10 in the moving support layer 12, the wheel 24 having a plurality of uniformly spaced spike-like or needle-like members 26 on its outer periphery. Foam roll coater made of open-cell foam material
28 is arranged to rotate in a bath containing the conductive liquid ink material 32. The forward movement of the carpet 10 on the belt 12 causes the rotating wheel 24 to move freely with the spike 26 about its axis. As the wheel 24 spins, the spikes penetrate into the open cell foam layer 28 and the conductive liquid 32 from the bath 30
Are saturated by the heat treatment and cover the outer surface of the spike 26. As the carpet tile 10 moves over the support layer, the spikes come in contact with the back surface of the carpet tile 10.
The spike 26 whose end is coated with the conductive liquid penetrates into the secondary backing layer 22 and the bitumen 20 to penetrate into the conductive precoat layer 18 and, when the spike is removed, deposit the conductive ink in the penetration hole 36. To form a conductive column 32 which forms an electrical path from the conductive precoat layer 18 to the backside of the secondary backing layer 22.

Rotation of the wheels forms a plurality of columns of conductive material 32 in a predetermined spaced linear arrangement across the entire back surface of the carpet tile 10 to a predetermined depth relative to the precoat layer, these being, for example, approximately depending on the backing coating and precoat thickness. It reaches 30 to 150 mils, especially 60 to 120 mils. As shown in more detail in FIG. 2, the backside of the carpet 10 is coated with a conductive layer of, for example, a conductive ink to form a dried conductive strip 34 over the entire backside of the carpet and the secondary backing layer 22. Connect the ends of column 32 at.

Then, the carpet prepared as shown in FIGS. 1 and 2 is used by placing it on the ground, and if desired, electrically connecting it with a wire grounded in the ground or using a conductive adhesive. An electrical connection may be made, but more typically it may simply be placed on the ground and in operation the static electricity accumulated on the surface 14 of the carpet will pass through the conductive fibers on the surface 14 and the conductive precoat layer and a plurality of layers. It goes through the column 32 to the strip 34 and is further grounded.

Although the improved carpet of the present invention and the method for manufacturing the same have been described above by the specific examples, it is necessary to make the fiber surface of the carpet conductive or make the precoat conductive according to the desired type of conductivity. Not. This is because it is often desirable to form a thin column of conductive material throughout the backing layer, either pre-coated or extending to the primary sheet, to form electrical passageways across the face thickness of the carpet tile, especially with a thicker backing layer. This is advantageous when it is made of a non-conductive material, because it actually acts as an electric insulating material for a surface covering material such as bitumen or lime-filled bitumen.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view of a method for manufacturing a conductive carpet tile according to the present invention, and FIG. 2 is a rear view of the carpet tile according to FIG. 10 …… Carpet tile, 12 …… Belt 14 …… Yarn, 18 …… Latex layer 20 …… Lining layer, 22 …… Lining sheet 24 …… Rotating wheel, 26 …… Needle-like member. 32 …… Ink material

Claims (12)

[Claims] 1. A comparatively thick backing layer comprising (a) a fibrous surface material, (b) a primary backing sheet for fixing the fibrous surface material, and (c) an electrically insulating backing material and having a back surface. , (D) a plurality of columns of thin conductive material forming a conductive path from the back surface of the backing layer to the back surface of the fiber surface material, said columns extending apart and perpendicular to the surface of the fiber surface layer. A fibrous floor covering material having improved conductivity. 2. A covering material according to claim 1, further comprising a conductive coating layer strip for electrically connecting a plurality of conductive columns on the back surface of the backing layer. 3. The covering of claim 1 having a bulk electrical resistance of less than about 1 × 10 ⁸ Ω / square. 4. A method for producing an antistatic or conductive surface covering comprising a layer of fibrous surface material secured to a primary backing sheet, and further comprising a non-conductive backing layer having a backside, in the production of a backing layer. Form a plurality of spaced columns of thin conductive material to form a conductive path from the back surface of the surface material to the back surface of the fibrous material. A method of manufacturing an antistatic or conductive surface covering material, which comprises forming the surface covering material with improved low electrical resistance. 5. The method according to claim 4, wherein a thin spike-shaped member containing a conductive material is allowed to penetrate into the backing layer, and the thin spike-shaped member is removed from the backing layer to form a column of the conductive material in the backing layer. The method described. 6. The method of claim 5 wherein the thin spike-like member has a coating of liquid conductive ink material, said ink material containing conductive carbon black or metal particles. 7. The method of claim 4 wherein the fiber facing material comprises a conductive fiber facing material. 8. The surface covering material has a conductive precoat layer on the back surface of the primary backing sheet, and forms a thin spike-like column protruding from the back surface of the backing layer into the conductive precoat layer. Method described in section. 9. The method according to claim 4, wherein a plurality of ends of the conductive material on the back surface of the backing layer are connected to the conductive layer. 10. A conductive strip is coated to connect a conductive material extending to the back surface of the backing layer, an electric path for the plurality of conductive materials to reach the strip is formed, and a ground is provided when the surface covering material is attached. The method according to claim 9, characterized in that 11. A rotary motion of the wheel, wherein a plurality of spaced spike-like members on the front surface of the rotating wheel are moved in an intruding relationship with respect to the back surface of the carpet tile to coat the outer surface of the spike-like member with a conductive liquid ink material. The liquid coating spike-like member is penetrated into the back surface of the backing layer of the carpet to form a plurality of spaced penetration holes in the back surface of the backing layer extending to the precoat layer, and the liquid is introduced into these penetration holes. 5. A method as claimed in claim 4, in which the spikes are deposited and uncoated during rotation of the wheel for further coating and penetration. 12. A wrapping material according to claim 1 wherein the fiber facing material comprises a conductive synthetic fiber facing material and the backing layer comprises bitumen.